Computational Fluid Dynamics (CFD) is an enormously rich field on its
own. Originally covered by the finite difference method, the CFD field
equations are nowadays usually solved by the finite volume
method. Occasionally one also encounters finite element CFD codes. Whereas the
finite element method can be considered as a code for which the primary
variables (i.e. the variables solved for in the ensuing linear equation system
such as the displacements) are determined at the nodes and the secondary
variables (derived from the primary ones by differentiation, such as the
strains) at the integration points, the finite volume method is characterized
by the primary variables (such as velocity, static temperature, static
pressure... in CFD calculations)
being determined at the center point of the elements (usually called
cells). Thus, the size of the equation system corresponds to the number of
elements. In what follows frequent
recourse will be taken to references [61] and [22]